added test

Author: lindt

features/images.feature

@@ -0,0 +1,38 @@
+Feature: Images
+  As a Tester
+  I want to see which images have changed
+  so that I know where to test especially
+
+  Scenario: Diff Images
+    Given a file named "A.yml" with:
+      """
+      version: "2"
+      services:
+        one:
+          image: one:1
+        two:
+          image: two:1
+        four:
+          image: four:1
+      """
+    And a file named "B.yml" with:
+      """
+      version: "2"
+      services:
+        one:
+          image: one:1
+        two:
+          image: two:2
+        three:
+          image: three:1
+      """
+    When I run `bin/compose_diff --images A.yml B.yml`
+    Then it should pass with exactly:
+      """
+      | Name | Version |
+      | - | - |
+      | four | 1 (deleted) |
+      | one | 1 |
+      | three | 1 (new) |
+      | two | 2 (1) |
+      """

features/support/env.rb

@@ -0,0 +1 @@
+require 'aruba/cucumber'